Raised floors made up of panels of rectangular or square shape supported at their corners by props are often suitable for computor buildings, telephone exchanges and the like, since the large number of electrical cables leading to and from the apparatus can be conveniently accommodated in the under floor space. In order to provide adequate fire protection in these buildings the raised floors must be capable of preventing fires which start in the under floor space from spreading to the space above the floor for as long as possible.
Metal floor panels are of course non-combustible but the disadvantage of using these is that due to their high heat conductivity floor coverings quickly reach their flash point thus allowing fire to spread above the raised flooring. They also have the disadvantage that in the event of fire they quickly warp.
Wooden floor panels having their undersides covered with fire resistant metal are not particularly effective since fire can still travel up the narrow gaps between adjacent panels thus allowing fire to spread along the vertical edges of the panels to the top of the floor.
The invention has been made with these points in mind and an object of the invention is to provide a flooring panel for raised floors which will substantially avoid the above mentioned disadvantages.